(Revised Abstract) DESCRIPTION (provided by applicant): The Flow Cytometry Shared Service (FCSS) at the Arizona Cancer Center is highly utilized and supports research needs of Arizona Cancer Center members in several respects. Techniques the service routinely performs are as follows: detection and analysis of cell surface markers, cancer chemotherapeutic agents, reporter dyes, intracellular proteins, cell cycle analysis/apoptosis studies, soluble cytokine detection and cell sorting. A long-term goal of the service is to continue to provide state-of-the-art data collection, analysis and cell sorting capabilities to Arizona Cancer Center members. To accomplish this goal, the service collects and analyzes data and performs cell sorting from 9:00 a.m. until 6:00 p.m. It also works in consultation with investigators to develop and optimize new assays and techniques that become available for all users. Because the FCSS processes many different samples from many different investigators, it can connect investigators interested in the same techniques. Instrument use is nearly constant during working hours and sometimes after hours. Current user fees for the shared service are $40 per hour. The flow cytometry specialist performs quality control every day to ensure that the FACScan and FACSVantage instruments are calibrated properly. The flow cytometry specialist plays a critical role in helping the facility run smoothly by solving scheduling problems; performing minor equipment maintenance, billing investigators, and helping users analyze data. Overall, the FCSS is a very successful and highly utilized service, supporting cellular analysis for Arizona Cancer Center investigators.